Fan attachment clip for heat sink

ABSTRACT

A clip secures a pin fin heat sink to a fan. The clip includes a frame having a width which can be wedged between the fins of the heat sink. Blades extend downwardly from the frame and bear against the heat sink fins to secure the frame to the heat sink. The clip is locked in place by barbs which extend upwardly to engage the fins of the heat sink when the clip is urged in a direction which would free it of the heat sink.

RELATED APPLICATIONS

This is a division of application Ser. No. 08/621,167, filed on Mar. 22,1996 now U.S. Pat. No. 5,677,829 of Donald Clemens entitled "FanAttachment Clip For Heat Sink", which is a continuation-in-part of Ser.No. 08/482,011 filed Jun. 7, 1995, now U.S. Pat. No. 5,590,025 grantedDec. 31, 1996.

BACKGROUND OF THE INVENTION

This invention relates to a clip for attaching a fan to a heatdissipating heat sink.

Many semiconductor devices generate heat during operation which must bedissipated to avoid damage to the device. Some such devices havepower-handling limitations which are largely determined by their abilityto expel internally-generated heat and thereby avoid general orlocalized thermal degradations or failures within them.

In some semiconductor devices, the internally-generated heat isdissipated sufficiently by the enclosure, header or leads of the device.In many semiconductor devices, however, it is necessary to aid thedissipation of internally-generated heat by the use of heat sinks. Awide variety of heat sink designs have been employed for dissipation ofinternally-generated heat from electronic device packages which housesemiconductor devices. For the purposes of the present invention, a heatsink is a body of metal or like material which is placed in contact withan electronic device package for transferring internally-generated heatfrom the semiconductor device contained in the electronic device packageand for rapid dissipation of the internally-generated heat to theatmosphere by conduction, convection and/or radiation.

U.S. Pat. No. 4,884,331--Hinshaw shows a widely used heat sink commonlyreferred to as a pin fin heat sink. The heat sink has rows and columnsof upstanding parallel fins. The heat sinks are formed by firstextruding rows of upstanding fins and then cross-cutting the fins toform rows and columns of pin fins.

These devices are frequently adequate to cool electronic devices bythemselves. However, in many applications, it is desirable to add a fanwhich blows cooling air over the fins of the heat sink. The prior arttechnique of securing a fan to heat sink is by inserting a screw, orlike fastener, through the mounting holes of the fan into the spacebetween upstanding pin fins. This is not satisfactory, because often aspace between pin fins does not line up with all of the mounting holeson the fan. The clip of the present invention obviates this problem.

It is an object of the present invention to provide a clip which makesthe assembly of the fan to a heat sink much easier.

SUMMARY OF THE INVENTION

In accordance with the present invention, a clip includes a frame havinga width which can be wedged between the fins of the heat sink. The cliphas means to secure the fan to the frame. The frame is wedged betweenthe fins of the heat sink and then locked in place. The rectangularshape of the frame fits between rows and columns of fins on the heatsink.

The frame is formed from a sheet of resilient metal. The blades extenddownwardly from the frame. Blades are inserted between the columns ofpin fins in the space formed by cross-cutting.

The clip of the present invention has important advantages whenassembled with the blade between columns of pin fins formed bycross-cutting. The cross-cut gap between columns of pin fins is narrowand of a constant dimension. Because of this, the clip of the presentinvention will always provide good engagement and locking in the heatsink. On the other hand, the gap between the extruded rows of pin finsvaries depending upon the size of the heat sink. One size clip will notwedge in the extruded rows of all heat sinks.

The insertion of the clip of the present invention into cross-cut gapsbetween columns of pin fins has another important advantage. The finsoften have better strength in the extruded direction and this is thedirection against which the locking force of the clip is applied.

The clip of the present invention is adaptable to different sizes ofheat sinks and it is adaptable to different types of fans. The clip ofthe present invention can be inserted into heat sinks having relativelylong or relatively short pin fins. In the longer pin fin heat sinks, theclip does not bottom out at the base, but the clip is securely locked inplace.

The clip can be used to mount fans of various types. These include fanswhich have slots or holes at the corners.

Further in accordance with the invention, the blades of the frame havearcuate cut-outs. The arcuate cut-out traps a Z clip in the heat sink.This aids in the assembly of a heat sink with a socket wherein the Zclip secures the heat sink to an electronic device.

Further in accordance with the invention, the extruded fins of the heatsink have a ridge or a notch to hold the frame in place in the heatsink. This prevents the fan assembly from pulling off the heat sink. Theridge or notch is extruded into the extrusion before it is cross-cut tomake a pin fin heat sink, but the invention can also be used on anextruded heat sink.

In accordance with another modification of the invention, the fins ofthe heat sink are serrated to form a series of notches and ridges. Thefan clip is pushed to a desired, appropriate depth. The clip fits intothe notch at this depth. Instead of being latched into a specific notchor ridge, some flexibility in positioning the clip on the heat sink isprovided.

Further in accordance with the invention, a nub on the clip prevents theclip and fan from sliding sideways in the heat sink. The nub fitsbetween two pins in a pin fin heat sink to prevent sideways motion.

The foregoing and other objects, features and advantages of theinvention will be better understood from the following more detaileddescription and appended claims.

SHORT DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a fan, a heat sink and the clip of thepresent invention;

FIG. 2 is a top view of the clip;

FIG. 2A is a view of the clip on the line A--A;

FIG. 3 is a front view of the clip;

FIG. 4 is a side view of the clip;

FIG. 5 is an exploded view of a fan, the clip of the present invention,a Z-spring retainer, a pin fin heat sink, an electronic device, and asocket;

FIG. 6 shows a modification of the heat sink with a notch for holdingthe clip in place;

FIG. 7 is an enlarged view of the notch of FIG. 6;

FIG. 8 shows the clip in place on the heat sink;

FIG. 9 is another modification wherein a notch on the fins of the heatsink holds the clip in place;

FIG. 10 shows a modification in which the fins are serrated to form aseries of notches and ridges to hold the clip in place at a desireddepth of the heat sink;

FIG. 11 is an enlarged view of a fin of FIG. 10; and

FIG. 12 shows a modification in which the blade of the clip has a nub toprevent sideways movement of the clip.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The clip of the prevent invention includes a frame 10 having a widthwhich can be wedged between the fins of the heat sink 12. Heat sink 12is of the type made in accordance with the aforementioned '331 Hinshawpatent. It has pin fins 14, 16, . . . 18 in one row and similar fins inparallel rows. These rows of fins are extruded during the manufacturingprocess. Then, the rows of fins are cross-cut to form columns of pinfins. For example, pin fins 18, 20 . . . 22 are in a first column andthere are successive parallel columns of pin fins.

The clip has a width which can be wedged between parallel columns of pinfins. Blades 24 and 26 extend downwardly from the frame. (Hereinafterthe words "upwardly" and "downwardly" will be used to describe elementsas viewed in the drawings, but it will be understood that these arerelative terms which depend upon the direction from which those elementsare viewed.) Blades 24 and 26 bear against the fins to secure the framein the heat sink after it has been inserted therein. Sides 23 and 25 ofthe frame fit between adjacent columns of pin fins and sides 27 and 28fit between adjacent rows of pin fins.

Tabs 30, 32, 34 and 36 lock the frame in the heat sink after it has beeninserted. Tab 34 extends upwardly and outwardly from a bend line 38(FIG. 4) along which the tab is bent out of the plane of the blade. Thetab lockingly engages a fin against movement in the direction out of theheat sink. The tabs bite into the metal of the pin fins when upwardpressure is exerted so that the frame is locked in the heat sink.

The clip is made of resilient metal such as stainless or plated steel.The clip is formed from a sheet of this resilient metal such that thewidth of the sheet forms the blades 24 and 26 which fit between thecolumns of the pin fins. Each of the blades spans one or more rows ofthe pin fins.

Upstanding corner posts 40-43 engage the fan 11 to secure it to theframe 10. As best shown in FIG. 2A, each corner post is bifurcated sothat it compresses as it is pushed into the slots 44 of the fan. Thecorner posts may also be pushed into mounting holes in the fan. Eachcorner post has barbs 47, 48. These barbs snap over the top lip of theslots 44-46 to lock the fan to the clip. Alternatively, when a fan hasholes, instead of slots, the barbs dig into the hole to lock the fan tothe clip.

Two edges 49 of the frame are turned upwardly to form a strengtheningrib. This provides stability to the frame.

Each of the blades has an arcuate cut-out 50. Arcuate cut-out 50accommodates a wire clip 52 (FIG. 5) which secures the heat sink to asocket. Pages 15-29 of the Thermalloy catalog 90-HS-11, ThermalloySemiconductor Accessories, show clips for attaching heat sinks toelectronic devices. Z-clip 52 is trapped by the arcuate cut-outs 50 inthe blades of the clip 10. The Z clip is engaged by the protrusion 53 onsocket 54. In this manner, the assembly of socket 54, electronic device55, heat sink 12, clip 10 and fan 11 are held together.

FIGS. 6 and 7 show a modification in which the heat sink fin 20 has aridge 58 which holds the clip in place on the heat sink. The ridge 58 isformed during the extrusion of the fins 18, 20, . . . 22. The ridge 58holds the fan assembly including the frame on the heat sink so that theframe cannot be pulled off the heat sink. The ridge 58 is extruded onthe fin before the heat sink is cross-cut to make a pin fin heat sink.

FIG. 8 shows the frame 10 in place on the heat sink with the tabs 32, 34securely locked under projection 58.

FIG. 9 shows another modification in which a notch 59 is formed in atleast one extruded fin to hold the clip, and fan assembly, on the heatsink. In similar manner, the tabs 30, 32, 34, and 36 snap into a notchon the fins to hold the clip in place.

FIGS. 10 and 11 show a modification in which the fins of the heat sinkare serrated to form a series of ridges and notches which hold the frameat a desired depth in the heat sink. The frame is pushed to anappropriate depth in the heat sink rather than hooking onto a specificnotch. This allows flexibility in assembling the heat sink, frame andfan into an assembly.

As shown in FIG. 12, the blade has a nub 60 which fits between two rowsof fins. This prevents sideways motion of the frame. The nub 60 is bentout of the plane of the blade to form a notch in the blade. This notchcan be used to secure a wire clip in the same manner as the cut-out 50of FIGS. 1 and 4.

Other embodiments are within the true spirit and scope of the invention.The appended claims, are therefore, intended to cover all suchembodiments.

What is claimed is:
 1. The combination of a heat sink and a clip forsecuring said heat sink to a fan for cooling said heat sink comprising:aclip having a rectangular, open, frame; a blade extending downwardlyfrom said frame; a tab extending outwardly from said blade; a heat sinkhaving rows and columns of upstanding fins; and a projection on at leastone of said fins of said heat sink, said tab engaging said projectionfor holding said frame on said heat sink.
 2. The combination recited inclaim 1 wherein the projection on said heat sink is a ridge on at leastone of said upstanding fins.
 3. The combination recited in claim 1wherein the projection on said heat sink is a side of a notch in atleast one of said fins.
 4. The combination recited in claim 1 furthercomprising:a plurality of said blades on said clip; and a projection ona plurality of said fins, a tab on each blade engaging projections on afin to hold said frame in said heat sink.
 5. A clip for securing a heatsink having upstanding parallel fins to a fan for cooling said sinkcomprising:a rectangular, open, frame; means adapted to secure said fanto said frame including upstanding corner posts on said frame adapted toengage said fan to secure it to said frame; and a blade extendingdownwardly from said frame adapted to bear against fins to secure saidframe on said heat sink, said blade having a downwardly facing arcuatecutout which accommodates a wire clip adapted for securing said heatsink to a socket.
 6. The clip recited in claim 5 wherein said frameincludes two blades extending downwardly from opposite sides of saidframe.
 7. The clip recited in claim 5 further comprising:means adaptedto lock said frame to the fins of said heat sink.
 8. The clip recited inclaim 6, wherein said means adapted to lock includes tabs extending fromsaid blade, said tabs extending upwardly and outwardly from a bend linealong which said tabs are bent out of the plane of said blade tolockingly engage said fins against movement in the upward direction. 9.The clip recited in claim 5 wherein said frame is formed from a sheet ofresilient metal.
 10. The clip recited in claim 5 wherein said means forsecuring said fan to said frame includes upstanding corner posts adaptedto engage said fan to secure it to said frame.
 11. The clip recited inclaim 10 wherein each corner post is bifurcated.
 12. The clip recited inclaim 11 wherein each corner post has a barb at the top thereof.
 13. Theclip recited in claim 5 wherein at least one edge of said frame isturned upwardly to form a strengthening rib to provide stability to saidframe.
 14. A clip for securing a heat sink having upstanding parallel toa fan for cooling said heat sink comprising:a rectangular, open, frame;means adaptive to secure said fan to said frame including upstandingcorner posts on said frame adapted to engage said fan to secure to saidframe; a blade extending downwardly from said frame adapted to bearagainst said fins to secure said frame on said heat sink, and at leastone tab extending outwardly from said blade to lock said frame in saidheat sink after it has been inserted.
 15. The clip recited in claim 14wherein said frame is formed from a sheet of said resilient metal. 16.The clip recited in claim 15 wherein the width of said sheet forms saidblades, said blades abeing adapted to between said columns of pin fins.17. The clip recited in claim 16 wherein said blade is adapted to spanat least two rows of pin fins.
 18. The clip recited in claim 14, whereinsaid means for securing said fan to said frame includes upstandingcorner posts adapted to engage said fan to secure it to said frame. 19.The clip recited in claim 18 wherein each corner post is bifurated. 20.The clip recited in claim 18 wherein each corner post has a barb at thetop thereof.
 21. The clip recited in claim 14 wherein at least one edgeof said frame is turned upwardly to form a strengthening rib to providestability to said frame.
 22. The clip recited in claim 14 wherein saidblade has a downwardly facing arcuate cut-out which accommodates a wireclip adaptive for securing said heat sink to a socket.
 23. An assemblyincluding:a pin fin heat sink having upstanding parallel fins; a fan forcooling said heat sink; a socket an electronic device between saidsocket and said heat sink and a clip for securing said heat sink to saidfan comprising:a rectangular, open frame; means on said frame forsecuring said fan to said frame; and a blade extending downwardly fromsaid frame, said blade bearing against said fins to secure said frame onsaid heat sink, said blade having a downwardly facing arcuate cut-outwhich accommodates a wire clip to trap said wire clip in said heat sink.24. An assembly including:a pin fin heat sink having upstanding parallelfins; a fan for cooling said heat sink; a socket an electronic devicebetween said socket and said heat sink and a clip for securing said heatsink to said fan comprising:a rectangular, open frame; means on saidframe for securing said fan to said frame; and a blade extendingdownwardly from said frame, said blade bearing against said fins tosecure said frame to said heat sink, and at least one tab extendingoutwardly from said blade to lock said frame in said heat sink.